Covering or finish



June 25, 1940. v. LEFEBURE COVERING 0R FINISH Filed Dec. 7, 1937 viciorLgebul'e. 2% ZM Wow-w Patented June 25, 1940 UNITED STATES PATENT OFEICE COVERING OR FINISH Victor Lefebure, London, England, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain 5 Claims.

This invention relates to finishes for ceilings, floors, walls and other surfaces.

It is of great advantage when putting a finish, particularly a decorative finish, on to a wall to utilise a preformed finish which can be affixed by comparatively unskilled labour. Unfortunately such a finish if made of plaster or cement is very fragile and difiicult to carry and handle without breakage.

This invention has as an object to provide a method of affixing plaster or cement finishes by means of preformed units which can be handled with the same facility as wall board or plaster board. Further objects will appear hereinafter.

These objects are accomplished by the following invention. I have found that I can successfully apply such a finish if I use a plaster board or other material comprising a mineral core having a relatively thin outer covering of fibrous material. This is mounted on or secured in any suitable manner to the surface to be finished, after which the exposed fibrous covering is removed by stripping and/or abrasion. If the surface to be finished consists of masonry or the like the board is preferably aflixed thereto by means of cement or plaster, e. g. anhydrite plaster, which may form a continuous or broken layer between the board and the surface to be finished.

According to another form of my invention, plaster board or the like is keyed to a concrete wall, ceiling, floor or the like by allowing the concrete to set in contact with the board, which forms part of the mould or a lining for the same, after which the exposed fibrous covering of the board is removed by stripping and/or abrasion.

The composite sheet materials described in my co-pending United States application Serial No. 178,625 are particularly suitable for this purpose as one or both coverings can be readily removed from. the underlying plaster, cement or the like. Thus one covering may be removed prior to application of the board to the surface to be finished, the exposed surface of the mineral core being then cemented to the surface or background to be finished, after which the exposed fibrous covering is removed as described.

It will be understood that any kind of plaster, cement or the like may be used to form the mineral core. In some cases mixes containing gas or foam producing agents, leading to void or cellular set masses which have the advantage of lightness, combined with enhanced heat and sound insulating properties, may be employed. Due regard must be paid to the necessity for selecting suitable fibrous coverings that will bond with the wet plastic; for example, standard pulp board does not bond W811 with Portland cement mixes, but a good bond is obtained if a pulp board is used containing a high percentage of 5 .x; asbestos. Plaster of Paris and anhydrite binders or cements are the chief materials that come into question. An important case is when the mineral core is of a decorative nature, e. g. it may consist of coloured, mottled or veined plaster, or of a plaster containing coloured aggregates, which can be abraded to give a terrazzo surface. Reinforcements such as wire gauze or perforated pulp board or other suitable fibrous material may be included in the mineral core if desired. Such reinforcement is advantageously placed near the surface of the core, and in some cases may be provided adjacent both surfaces.

In stripping the covering from the side of the material to be exposed, various methods may be employed according to the nature of the material, examples being given below. The top surface of the core exposed by the removal of the covering may be left as such, or it may be rubbed with an abrasive to bring out veined or terrazzo effects. The final surface may if desired be painted, lacquered or impregnated with oil or wax or other filling material. It is sometimes advantageous to waterproof the fibrous covering next to the surface to be finished, e. g. by applying an aqueous emulsion of bitumen to the covering prior to affixing the material to the surface to be finished, or by using a material the covering of which has been rendered waterproof during its manufacture.

The following examples illustrate but do not limit the invention.

Example 1 Example 2 A sheet material is made by a continuous sheeting method in a similar manner to plaster board, one or both of the coverings consisting of two or 55 more fibrous layers united by a water soluble or water softening adhesive. The layer to be placed next to the plaster is thin compared with the total thickness of the covering, e. g. it may be made of thin paper.

When the surface of the final product is moisened, after the material has been aifixed to the surface to be finished the water penetrates to the adhesive bond between the relatively thin fibrous layer and the superposed layer or layers, and the latter may be stripped off, leaving the plaster core with a thin fibrous covering which can easily be removed by washing and rubbing. This method has the advantage of protecting the surface of the plaster core from disfigurement due to rough stripping treatment, and is especially applicable where the core is of a decorative nature.

Example 3 A sheet material is made by a continuous sheeting method in a similar manner to plaster board, one or both of the coverings consisting of fibrous board which on account of heavy compacting and/or sizing or similar treatment gives a weak bond with the plaster.

The coverings can be stripped off the core when required, without the necessity for moistening them. This method is chiefly applicable to reinforced sheets or to sheets of ample thickness to withstand the stresses caused by handling and fixing and by the stripping of the coverings.

Example 4 A sheet material is made by a continuous sheeting method in a similar manner to plaster board, one or both of the coverings consisting of an absorbent fibrous board of fairly low mechanical strength.

The product is of sufficient strength. to with stand handling and transport without damage to the plaster core, and the coverings can be removed by mild abrasive treatment, wire brushing, or by moistening followed by stripping.

In order to further illustrate the invention, reference is made to the accompanying drawing in which:

Fig. 1 is an enlarged cross-sectional view of a portion of plasterboard employed in carrying out the invention, and

Fig. 2. is a perspective view showing two of the special boards used according to the invention to provide a covering or finish for a wall or the like.

Referring to the drawing, l is the core of decorative or other special type of material which is to form the finished wall surface after the removal of the liner. In the example illustrated, a composite liner is employed comprising a thin back member 2 mounted upon and bonded to the core and a top or stripping member I which is bonded or united to back member 2 by means of a water soluble or water softening adhesive 3, the adhesive forming a zone of potential weakness. 5 is the bottom liner of the plasterboard and may be ordinary plasterboard liner, which may be rendered water-resistant by known methods. Instead of the com-- posite liner, a one-piece liner may be used, which is bonded or secured to the core, as by adhesive, so as to form a zone of potential weakness between the liner and the core.

Fig. 2 shows two of the special boards above described applied to or erected against wall or backing 6 of plasterboard to provide a cover- ..ing or finish therefor, plaster of Paris being used to stick or cement them to the backing. One of these boards (to the left in Fig. 2) is shown with the top member I of the composite liner in the process of being stripped off, after it has been wetted, to thus expose the thinner back member Back member 2 can be subsequently removed very easily by wetting slightly and rubbing gently with a damp cloth or with wire Wool to expose the preformed finish of the core 4, as shown by the board illustrated to the right in Fig. 2.

Among the advantages of the invention are the following:

(1) Acoustic pZaster.-By employing a plaster board containing a core of so-called acoustic plaster (void or cellular plaster) and subse quently removing the outer fibrous covering, a large area of acoustic plaster is exposed which presents, in some cases after slight abrasion,

a uniform surface as regards appearance and acoustic properties. Hitherto, when the plasters were applied by trowelling or even by spraying, it was extremely difficult to obtain surfaces of the desired uniformity in these respects. The acoustic plaster board, however, may be made by a continuous sheeting method under conditions ensuring absolute uniformity of structure.

(2) Flooring c0mposi'ti0ns.By employing a plaster board containing a core of flooring COll'l-- position, which may be of a decorative nature, and removing the exposed fibrous covering only when the finished floor is required, damage to the fioor by workmen is avoided. The floor board is applied in large sheets or tiles and is protected by the outer fibrous covering during fixing operations and until all operations likely to result in damage to the floor have been completed.

(3) Walls or floors-By grouting the joints between the sheets or tiles of plaster board while I the outer protective fibrous covering is still in position, damage to the plaster or cement surface as a result of grouting is avoided. When the fibrous covering is removed the grouting material projects above the surface of the plaster but can readily be abraded fiush with the latter. If it is necessary to abrade the plaster surface, e. g. to obtain a terrazzo effect or to remove last traces of the fibrous covering, the grouting material is rubbed down at the same time.

(4) Coloured surfaces.--B;y using a plaster board containing a core of plain coloured plaster and subsequently removing the outer fibrous covering, a plaster surface is exposed which is perfectly uniform in colour. Such uniformity cannot be achieved by ordinary plastering technique.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it

is to be understood that I do not limit myself to the specific embodiments thereof, except as defined in the appended claims.

Iclaim:

l. A method of providing a surface with a preformed outer layer or finish comprising affixing to the surface a preformed composite comprising a mineral core having a preformed finish and at least one outer covering of fibrous material bonded to and protecting said finish,

there being a zone of potential weakness adjacent to and coextensive with at least one surface of said fibrous material, and then removing the said protective covering.

2. A method of providing a surface with a preformed outer layer or finish comprising aifixing to the surface a preformed composite com prising a mineral core having a preformed finish and at least one outer covering of fibrous material protecting said finish, said covering comprising a plurality of fibrous layers united by a water-soluble adhesive, the layer next to the preformed finish being thin compared with the total thickness of said covering, removing all but the thin layer by the application of Water, and then removing said thin layer to leave intact as an exposed surface said preformed finish. Y 3. A method of providing a surface with a preformed outer layer or finish comprising fixing to the surface a preformed composite comprising a mineral core having a preformed finish and at least one outer covering of fibrous material protecting said finish, said protective covering being firmly bonded to the mineral core by a Water-soluble adhesive, and then applying water to and removing the said protective covering to leave intact as an exposed surface said preformed finish.

4. A method of providing a surface with a preformed outer layer or finish comprising affixing to the surface a preformed composite comprising a mineral core having a preformed finish and at least one outer covering of fibrous material protecting said finish, weakening the said fibrous material by the application. of Water and removing it by abrasion to leave intact as an exposed surface said preformed finish.

5. A method of providing a surface With a preformed outer layer or finish comprising affixing to the surface a preformed composite comprising a mineral core having a preformed finish and at least one outer covering of fibrous material protecting said finish, weakening the said fibrous material by the application of water and removing it by stripping to leave intact as an exposed surface said preformed finish.

VIC TOR LEFEBUR'E. 

